arrow operator in swift

Question

I am trying to adopt a SDK written in objective-c in a swift project. The objective-c way to initialize the SDK is as follows:

@implementation ViewController
nokeSDK *nokelock;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    //INITIALIZE NOKE SDK
    nokelock = [[nokeSDK alloc] init];
    nokelock->cmd = [[nokecommand alloc] init];

I don't believe there is an equivalent to the arrow operator in swift, so is it possible to still initialize? I can't seem to find any info about his particular subject.

Answer 1

In Objective-C, a property is merely syntactic sugar for accessor methods; if, as is usually the case, these are a front for an instance variable, you can, with the right privacy access, bypass the accessor methods (or not have them in the first place) and get/set the instance variable directly. That's what your code is doing.

But Swift doesn't draw that distinction. A variable declared at the top level of a type declaration, in Swift, is a property; behind the scenes, a stored property has accessor methods, and you are passing through those automatically when you get/set the property. There is no separate instance variable to get/set.

To see what I mean, make a hybrid Swift / Objective-C app with class Thing whose interface looks like this:

@interface Thing : NSObject {
    @public
    NSString* s;
}

Now create the generated interface. You will see that, in Swift, s is nowhere to be seen.

Presumably, therefore, to rewrite your code, you'd need to turn cmd into a property, or at least provide a setter method. Otherwise, Swift will never be able to set the Objective-C cmd instance variable. Of course, if it is also up to you to rewrite nokeSDK in Swift, your problems are over, as you can now do whatever you like.